Doing Your Own Alignment

[Kennysgreen280zt]

I realize this is a super basic question. What are the steps for finding the centerline of the car?

[jt1]

http://album.hybridz.org/data/500/medium/pic_134.jpg

 

http://album.hybridz.org/data/500/medium/pic_132.jpg

 

I was at a circle track auction a while back where they sold this setup table. The table, turn plates, ramps and small tables sold as one lot, they sold the scales separately. I thought long and hard about it, but it was about 30 ft long, so moving it would have been a huge PITA, plus if I put in my shop I wouldn't have had much room for anything else. It's old tech by nascar standards, but would have been great for a hobbyist like myself. After a lot of thought, I passed on it.

 

It sold for $130.

 

Fail.

 

jt

[DrSideways]

I realize this is a super basic question. What are the steps for finding the centerline of the car?

 

 

Two plumb bobs hanging from the control arm bolts on the front. Make sure the bobs are on the same side of the bolt. ie. inside or outside of the bolt. Must be the same on each one.

 

I lay masking tape on the shop floor for the marks. Then measure between the two and find the front center.

 

On the rear you do the same using the inner control arm tube that runs fore/aft.

 

Now you have two marks on the floor at each end of the car. I use a laser to line up the two while extending the light line a few feet out of each end of the car.

 

This can take some time and patience. You could also use a chalk line.

 

From there I use a sheetrock T-Square to measure out to just beyond the wheels on each side.

 

Then I use the plumb bobs to set the strings beside the wheels from the new marks.

 

It takes time, but I get good results. Yours may vary. It is just easier for me to set this and ride height along with weighing all in the same day.

 

Hope this helps,

 

Alan

[johnc]

What Dr. said. Its important to level the car (use the top surface of the rocker panels and the top surface of the rear bulkhead or a bar across the top of the strut towers) first before running the plumb bobs down to the ground. A laser that shoots a horizontal and vertical plane helps a lot.

 

Also, don't let your dog in the shop when you're doing this as he will want to play with the plumb bobs.

[Mayolives]

[quote=DrSideways

Then I use the plumb bobs to set the strings beside the wheels from the new marks.

 

It takes time, but I get good results. Yours may vary. It is just easier for me to set this and ride height along with weighing all in the same day.

 

Alan,

 

 

I may be splitting hairs here but should I do the corner weights first, then adjust the ride height like JohnC recommended, and then proceed with the alignment details? Would the corner weights change significantly by realigning the car? What type of laser device would be better to use?

 

A side note on splitting hairs: I was in the G Force shop in PA, with my gear box and was told to check the input shaft run out in relation to the bell housing to be sure it was centered property. ( I had previously not installed the bushing that should be used on one of the bell housing bolts) I ask Bubba what was an executable run out number and he looked at me as if to say, "you are a dumb ass" and then said "as little as possible". When is good, good enough and when do you reach the point of diminishing returns.

[DrSideways]

As to what order to do things....

 

I try and get the ride height very close before alignment. The ride height is really determined by your bump steer range too. So keeping that close important.

 

Then I align the car with the sway bar or bars disconnected.

 

After that and pretty much the last thing before loading the car are the corner weights. Then I have someone connect the bar/bars with no pre-load while I am in the car.

 

Hopefully during the weighing I have not had to raise or lower a corner significantly enough to affect the alignment.

 

Early on when I did have to jack things around a lot I could move something in the car to get closer to begin with while the height and weight was where I wanted. Then realign. Then do a final weight.

 

From there things got easier. Now I can usually adjust the rear corners to get where I want to go. That leaves the front alone:)

 

Now if I can lose some ice cream maybe I can get to to running the car.

 

Alan